A PRELIMINARY REPORT ON CLAYS OF FLORIDA 149


 Physical Properties of Dexland Clay No. 3 (No. Lab. o-13).
 Plasticity, judged by feel............ Excellent.
 W ater of plasticity ................ -28.60%
 Linear air shrinkage................ 11.6 %
 Volume air shrinkage............... 33.8 %
 Modulus of rupture, average........ 656.6 pounds per square inch.
 Slaking test ....................... 2 days.
 Steel hard at cone 010.
 Overfires at cone 16.

 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950*C. 1.1 14.95 22.40 Pink.
 1050 1.9 14.30 29.75 Pink.
 1150 4.4 9.30 20.95 Buff.
 1190 4.4 7.83 19.20 Buff.
 1230 5.4 6.80 18.30 Cream.
 1310 5.4 5.35 12.10 Cream.
 1370 5.4 3.72 11.70 Gray.
 1430 6.4 3.32 10.80 Gray.

 Separated from the above clay by a thin sand parting is Dexland No. 3, which is a very plastic gray clay having the following physical properties:
 Physical Properties of Dexland Clay No. 3 .(Lab. No. o-13).
 Plasticity, judged by feel............ Excellent.
 W ater of plasticity ................ 29.40%
 Pore w ater ........................ 1.65%
 Shrinkage water .................... 27.75%
 Linear air shrinkage................ 10.6 %
 Volume air shrinkage............... 38.4 %
 Modulus of rupture, average........ 475.0 pounds per square inch.
 Slaking test ....................... 20 minutes.
 Steel hard at cone 05.
 Overfires at cone 16.

 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950*C. 0.5 16.80 33.65 Pink.
 1050 0.6 18.40 32.25 Cream.
 1150 6.4 12.25 18.00 Buff.
 1190 6.4 4.15 19.45 Buff.
 1230 6.4 2.58 10.10 Gray.
 1310 6.4 1.22 5.40 Gray.
 1370. 6.9 3.05 5.25 Gray.
 1430 4.4 6.75 Gray.

 Dexland Clay No. 4 is a gray, slightly sandy clay, exposed in both the upper and lower bluffs. It is the uppermost clay stratum having an